Publikationsdatum:
2017-04-04
Beschreibung:
In this work, we analyze the records of the Italian strong motion database
(ITACA, http://itaca.mi.ingv.it) with the aim of identifying stations affected by site effects
that are not captured by standard seismic classification schemes. In particular, we consider
four different site classifications, two of them based on geological/geophysical characteristics
and two driven by data. For each classification we develop a ground motion prediction
equation using a random effect approach to isolate the between-station and within-station
distribution of errors. The site coefficients obtained for the different classes confirm that
site amplification effects are significant for both the horizontal and vertical components.
The between-station error normalized to the standard deviation of the between-station error
distribution is then used to identify stations characterized by large errors, attributable to site
effects not accounted for by the classification schemes. The results show that large errors can
affect the predictions when the site effects are not uniquely related to the reduction of the
seismic impedance in the uppermost layers. For example, amplifications of ground motion
over the long period range are observed for stations installed within alluvial closed-shape
basins, as consequence of locally generated surface waves. For these stations, classifications
based on the horizontal to vertical response spectra ratio are not reliable, since amplifications
are also affecting the vertical component. Another interesting feature which emerges from
the analysis is the significant de-amplification of short period spectral ordinates that seems
to be related to stations typically set in at the foundation level of massive structures. To
increase the usefulness of the data set, the most important distinctive features of the strong
motion stations are documented in the ITACA database reports containing the instrument
information and the available geological-geotechnical data.
Beschreibung:
Published
Beschreibung:
1921-1939
Beschreibung:
4.1. Metodologie sismologiche per l'ingegneria sismica
Beschreibung:
JCR Journal
Beschreibung:
open
Schlagwort(e):
Ground motion prediction equation, site effects
;
ITACA
;
04. Solid Earth::04.06. Seismology::04.06.04. Ground motion
Repository-Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Materialart:
article
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